More or less air is NOT better - There is an exact amount of air needed to mix with the exact amount of gaz injected at idle. This is to provide idle air to the engine by bypassing the throttle plate. Set the 'Idle Air Mixture' screw to about 1/2 or 3/4 turn opened from fully seated. Note that at 610.0 mV you are off idle!! (ECM deactivates vacum engine mounts coil) So adjust acuratly to no more than 600mV +/- 2mV 600.0 mV) in the car powered by the computer circuitry. At this position you have base idle at which the TPS should read 0.6000 VDC (ie. Set the throtle plate to be almost fully shut closed plus a quarter turn of the screw so it is not sticking ie. You'll get a CEL if something is busted not for driveability issues like misfirings induced by lean mixtures (no CEL but degraded driveability regardless - Trust me I design computers). We are not even talking engine code here.
If a parameter is off you get bad driveability symptoms if the ECM can not detune the engine enough to compensate. In OBDII era everything is controled with extrim acuracy. The on-board OBDII ECM controls just about everything engine wise but for that it relies on a few bases set below. This article is about tuning your engine to get an happy ECM not race track nitrous tricks. Let me share some information not found elsewhere about how to set your Throtle Position Sensor (TPS) and throtle plate after cleaning the throttle body.
